This invention relates to sampling systems for liquids containing radioactive materials and, more particularly, to devices for separating gases contained in a sample stream of such a liquid prior to introduction into instrumentation which operates erratically or produces inaccurate measurements when gas bubbles are present.
In the operation of nuclear power plants and the like, various fluid samples are monitored by continuous or periodic sampling. The sample fluids quite commonly are liquids containing reasonably large amounts of gas bubbles which can cause erratic operation and/or adversely affect the accuracy of instrumentation in the sampling system, particularly flow meters and some types of analyzer. Consequently, at least most of the gas bubbles must be separated from the liquid prior to introduction into the instrumentation.
The internal volume of any device used with fluids containing radioactive materials should have as a small internal volume as possible in order to minimize the amount of shielding required to meet safety standards.
Gravity separation devices wherein the gas is allowed to bubble upwardly for removal from the top of the device and the liquid is removed from the bottom have been used for this purpose. Such devices typically include some type of float arrangement for preventing excess amounts of the liquid from flowing overboard. Small floats requiring a relatively small internal volume tend to eventually stick during use, making the separator ineffective. Furthermore, once such a float sticks, it is quite difficult to free it in an intense radioactive environment. On the other hand, floats with cage arrangements to minimize sticking require large internal volumes which necessitate an excessive amount of shielding.